The Hoverfly Attracting Property of a Methyl Salicylate-Containing (<i>E</i>)-β-Farnesene Analog (3e) and Potential Mechanism by Mediating the EcorOBP15 and EcorOR3

Using natural enemies provides a sustainable method to control major agricultural pests. Hoverflies are significant natural enemies of aphids and efficient pollinators. Herbivore-induced plant volatiles (HIPVs), including (<i>E</i>)-β-farnesene (EBF) and methyl salicylate (MeSA), are key olfactory cues mediating hoverflies behavior. Our previous work identified compound <b>3e</b>, an EBF analog containing a MeSA moiety, exhibited aphid-repelling and ladybug-attracting activities. However, whether <b>3e</b> can attract hoverflies remains unknown. Therefore, this study explored the attractant property and potential mechanism of <b>3e</b> toward hoverflies. Laboratory bioassays and field trials indicated <b>3e</b> has an obvious hoverfly attracting property. The attraction mechanism studies demonstrate that, similar to EBF, <b>3e</b> can interact with EcorOBP15 and EcorOR3, with its greater chemical softness, larger hydrophobic and charge regions enhancing these interactions. Furthermore, <b>3e</b> exhibited low toxicity to honeybees (<i>Apis mellifera</i>) and hoverflies (<i>Eupeodes corollae</i>). Consequently, <b>3e</b> could be a promising eco-friendly behavioral regulator for integrated aphid management in sustainable agriculture.